Method of sizing carbonate filled paper



Patented May 5, 1931 UNITED STATES PATENT OFFICE HAROLD ROBERT RAITON,OF LAWRENCE, MASSACHUSETTS, ASSIGNOR TO RAFFOLID PROCESS CORPORATION,CORPORATION OF MASSACHUSETTS METHOD OF SIZING CARBONATE FILLED PAPER NoDrawing.

This invention relates to a method of sizing paper and more particularlyto a method of sizing paper filled with carbonate filler.

The principal object of this invention is to provide a method of sizingpaper filled with carbonate filler wherein a paralfin emulsion made witha substantially water insoluble type emulsifying agent is added to apaper mix in the beater together with a potential fibre associatingagent, and a precipitant for such potential fibre associating agent isadded to the resulting mix at the wet end of the paper machine.

My invention is directed to sized paper such as is used for printingpurposes, for coating raw stock, or the like. It is not di rected towater-proof products such as prepared roofing or the like, nor toparaifined papers which normally have a paraflin finish,

which makes them substantially waterproof and usually translucent ortransparent and unsuited for the uses to which I wish to put my sizedpaper.

Other objects and advantages of this invention will become apparent fromthe course of the following description.

In my copending application Serial Number 304,176, filed Sept. 5,, 1928,I have described a method of sizing paper filled with carbonate fillerwherein there is added to fibrous material in a heater a paraflinemulsion made with a substantially water insoluble type emulsifyingagent, sodium resinate and alum and carbonate filler, and a restoringagent such as alum is added to the resulting mix at the wet end of thepaper machine. However, I have discovered that a certain measure ofsuccess may be obtained in sizing certain grades of paper filled withcarbonate filler by adding to the fibrous material and carbonate fillerin the beater a paraflin emulsi on of the character referred to togetherwith a potential fibre associating agent, preferably sodium resinate,and adding a precipitating agent such as alum to the resulting mix atthe wet end of the paper machine.

In the preferred practice of my process I add in a heater or the like topaper stock containing fibrous material and a carbonate filler,

0 a suitable amount of a paraflin emulsion made Application filedSeptember 5, 1928. Serial No. 304,177.

with a substantially water insoluble type emulsifying agent. Inpreparing such an emulsion I may use as an emulsifying agent asubstantially water insoluble material such as clay or even carbonatefiller itself. The method of making such emulsions is well known andthis method ordinarily comprises heating parafi'in above its meltingpoint and adding the melted paraflin with vigorous agitation to asuspension of the substantially water insoluble material in water whichis pref erably maintained at approximately the same temperature as thatof the melted paraffin. Vigorous agitation is meanwhile carried on andis continued while the emulsion is cooling. I then add to the fibrousmaterial and carbonate filler contained in a heater, mixer or similardevice the parafiin emulsion and a potential fibre associating agentsuch as sodium resinate, which serves to associate the emulsion with thefibre when a suitable precipitating agent therefor is subsequently addedat or subsequent to the dilution of the paper mix prior to its deliveryon to a webforming device. The amount of sodium resinate I may use isthat amount which by itself when precipitated with alum, in accordancewith my copending application Serial No. 304,172, filed Sept. 5, 1928,would not be suflicient to size the paper, but would produce asubstantially unsized paper. Thus the precipitate produced by sodiumresinate and alum does not in this case act as a sizing agent but as afibre associating agent. Of course, I may, if I desire, use a greaterquantity of sodium resinate, but it is to be pointed I the fibres andthe finished paper produced is satisfactorily sized.

Were no alum or equivalent material added at the wet end of the papermachine to the paper mix containing fibrous material, carbonate filler,parafiin emulsion of the type referred to, and sodium resinate, thepotential fibre associating agent would not be developed into a fibreassociating agent. In this case, of course, in so far as associating theemulsion with the fibre were concerned, it would be the same as if nosodium resinate were present and the paperfmix contained only fibrousmaterial, carbonate filler, and the paraffin emulsion of the typereferred to. In such case, of course, only-such parts of the paraffinemulsion as would be mechanically filtered out by the fibre would beretained thereon and the paper produced would not be satisfactorilysized, except possibly at the expense of a greatly increased quantity ofparaffin, which would be undesirable both because of certain mechanicalinstability as indicated below, as well as because of prohibitive cost.

By the addition of the alum at the wet end of the paper machine, thealum is thus added at a point where there will be a minimum of intimacyand time of contact of the constituents of the mix, before the paper webis formed. It is necessary as indicated to add the alum at or subsequentto the point of dilution of the mix, as I have found that if'it be addedwhen the mix is in relatively concentrated condition and particularlywhen the relatively concentrated mix is subjected to agitation as isnormal in stock chests, the fibre associating effect in the. mix is veryquickly deteriorated even to the point of complete destruction. Thefi-b-re associating effect even when the mix is in the diluted conditionis gradually deteriorated, but is substantially unaffected within thetime limits that the mix is maintained in the dilutestate in the usualpaper making procedure. Moreover, although agitation in the dilute statehastens to a certain extent the deterioration of the fibre associatingeffect, the speed of deterioration is not nearly so pronounced" as inthe concentrated condition, and from a practical standpoint I have foundthat the agitation to which the diluted mix is subjected prior todelivery onto the web-forming device does not deteriorate the fibreassociating effect to a substantial degree.

Of course the potential fibre associating agent, such as the sodiumresinate, may be added at any point prior to web formation other than inthe beater, even after the addition of the alum, but experiments do notindicate that any substantially better fibre associating effect isobtained thereby, al-' though the tendency to foam may be somewhatlessened,'and such addition therefore can be considered the substantialequivalent of adding sodium resinate in the beater.

The alum solution need not be added directly to the fibrous mix, but canbe added to the fresh water or white water, e. g. tray water, withwhich'the mix is diluted. If the alum be added to the tray water, only abrief time interval should elapse before the so treated tray water isused for dilution.

Although substantially more foam is'produced in the herein describedprocess than in the process referred to in my copending applicationSerial No. 304,176, filed Sept 5, 1928, (except possibly in thatmodification wherein sodium resinate would be added at the wet end ofthe paper machine after the alum addition), nevertheless the foam isaltered in character by the alum before the mix is passed onto theweb-forming device, so that what foam is not held back in the rifilersor the like is of such nature that it causes this process is of asatisfactory quality.

Moreover, inasmuch as theamount of alum used in the present process isless than that used in the process set forth in my copending applicationreferred to just above, the present process therefore results in a moreeconomical operation.

Although, clay is my preferred substantially water insoluble emulsifyingagent, I may use also other substantially water 1nsoluble emulsifyingagents which do not exist as such originally, such for example, as anyagent formed from two mutually precipitating materials which is adaptedto yield a substantially water insoluble coating around the individualparticles of paraffin. The method of making such emulsions is wellknown. Such an emulsion may be completely made prior to addition to thefibrous pulp, or it may be formed in the pulp by dispersing the paraflinoriginall in a soluble material which will prevent 1ts agglomeration inthe pulp mass, and then subsequently forming a substantially waterinsoluble coating on the dispersed paraffin particles by adding to thepulp mass and dispersed paraifin a material which will mutuallyprecipitate the original dispersing material into a substantially waterinsoluble layer or film around the dispersed paraffin particles.

Papers made in accordance with my invention are well sized but becauseof the relatively large size of the particles in com arison with thenonbreakable parafiin emu ion described in my copending applicationsSerial No. 304,170, filed Sept. 5, 1928, and Serial No. 304,17 3, filedSe t. 5, 1928, the sizing is not quite so well istributed through thepaper. Thus, it is usually desirable to use somewhat more paraflin thanin the copending applications referred to just above. Moreover, in orderto secure uniform distributage for preparing certain grades of paperwhere the requirements are not so exacting.-

The emulsion herein employed, although reasonably resistant to chemicalagencies, especially if the substantially waterinsoluble emulsifyingagent employed be also substantially acid insoluble, has certain defectsfrom a mechanical standpoint which should be taken into account in itsuse. The chief difliculty is'that this emulsion has a tendencyto bemechanically unstable, and when sub ected ,to pressure as by the actionof the beater, some of the particles may have their protective coatingof clay removed, and thus be released from emulsified condition withconsequent release of articles of free paraflin in the stock, which havea tendency to agglomerate and cause trouble in the paper making process.For this reason it is desirable to beat the fibre prior to the additionof the emulsion and then raise the beater roll just prior to adding theemulsion, using-the roll merely for mixing rather than for beatingpurposes thereafter in order to prevent the breakdown of the emulsion bythe beater.

The action of the fibre associating agent does not seem to have anoticeable breaking effect on the emulsion itself, and thus the paraffinis not thereby directly released from emulsion, but the same defectregarding the action of mechanical agencies on the emulsion as set forthabove seems to be inherent in the emulsion whether alone, or whenassociated with the fibre associating agent.

, An illustrative furnish which may advantageously be used in practicingmy invention is as follows:

Materials added in the beater Pounds Fibrous furnish (e. g. sulphlte andsgda pulps) 1700 Rosin (added in the form of sodium resmate) 10 Paraflln(added in the form .of a substantially water insoluble emulsifier typeof emulsion) Calfiiun; carbonate magnesium hydroxide (carbonate 300Material added proportionately and continuouslg on dilution Pounds Alum(ordinary Al (S0 .18 H O 65 Anotherillustr'ative furnish is as follows:

Mdtem'als added in the beater Pounds Fibrous furnish (e. g.approximately equal parts of 1 -sulph1te, soda and 01d paper stocks)1800 Rosin (added in the form of sodium resinate) 10 Paraflln (added inthe form of a substantially water insoluble emulsifier type ofemulsion), v Calcium carbonate magnesium hydroxide (carbonate. -fl11er)200 Mdte zal. added proportionatety and corttnw ously. on ditutz'onPounds Alum (ordinary A1,(so.),.1sH,o 65

In the above formulae the weights of carbonate filler refer to bone drybasis, the weights of all other ingredients being'given on the air drybasis. a

In regard to the araffin used, it is to be understood that eit er low orhigh melting point material can be employed. The socalled fully refinedparaffin is entirely satis- .factory since it does not impartobjectionable color to white sheets. However, for purposes of economy,it is often desirable to use a less pure material such for example asthe material which is commonly known to the trade as semi-refinedparaflin scale. containing approximately 1-2 per cent. of oil and wateras impurities, which material gives satisfacg tory results.

Such material will perhaps in-certain cases have varyin melting points,but one particular sam e used, for example, had a melting point 0approximately 115 F. (46 C.). Other even more impure araflin may beused, especially if the color whiteness) requirements of the finishedpaper are not too exacting, or if papers, other than white, are to bemade.

In place of alum in the practice of'my process I may employ with ameasure of success an acid such as sulfuric acid ,(H SO In place ofsodium resina-te I may use satis- 5 factorily in the practice of myprocess other soaps, such as the oleates, or any partially or completelysaponified material, such as saponified beeswax.

By the term carbonate filler as employed 1,10

' herein, is intended to be included calcium carbonate, of which limemud from the causticizing process is one form; calcium carbonatemagnesium basic carbonate employed in the paper disclosed in my U. S.Patent No.

0 1,595,416; calcium carbonate magnesium hydrox'ide disclosed in my -U.S. Patent No. 1,415,391; or other substantially water insoluble normalor basic carbonates of alkaline earth metals, (which expression isherein intended to include magnesium) or compounds,

5 stituents or the like containing one or more compounds of thecharacter referred to, such 18 as old papers or similar papers, broke,or the like.

By the term wet end of the paper machine is intended to be includedthose instrumentalities employed in paper manufacture by which and/or inwhich a relatively concentrated paper mix is diluted, and treated,conveyed or fed up to the point of web-formation, such as the mixingbox, regulating and proportioning devices, rifiiers, troughs, screens,head boxes, inlets, and the like, including also instrumentalities usedin the white water cycle.

When I employ the term paraffin herein, I mean paraffin wax, which issolid at ordinary or room temperature. I do not mean to restrict myselfonly to the paraffin hydrocarbons, but mean to include in this term allthe hydrocarbons of a waxy nature substantially unsaponifiable and inertto acidic and alkaline materials under ordinary conditions oftemperature and pressure, whether derived from petroleum, shale,lignite, earth wax, or other natural or artificial sources. I do not,however, mean to include in this term material of a pitchy nature, suchas bitumen or asphalt.

Where I use the term sodium resinate it is to be understood that I meanit to include any material produced by the action of alkali, generallyin aqueous solution, on rosin, or on natural or synthetic resin acid oracids, regardless of the exact composition of the product, or thevarying composition which different samples may possess.

lVhen I use the word paper herein, I use it in the broad sense toinclude products of manufacture of all types and of all weights andthicknesses, which contain as an essential constituent a considerableamount of prepared fibre and which are capable of being produced on aFourdrinier, cylinder, or other forming, felting, shaping or moldingmachine.

While I have described in detail the preferred embodiment of myinvention, it is to be understood that the details of procedure, theproportions of ingredients, and the arrangement of steps may be widelyVaried without departing from the spirit of the invention or the scopeof the subjoined claims.

I claim:

1. The method of sizing paper filled with carbonate filler comprismgmixing with fibrous material carbonate filler, a paraffin emulsion madewith a substantially water insoluble type emulsifying agent, and apotential fibre associating agent, and thereafter adding to theresulting mix a precipitant for said potential fibre associating agentunder conditions favoring the minimizing of the time of contact of theconstituents of the mix, and thereafter making paper therefrom.

2. The method of sizing paper filled with carbonate filler comprisingmixing with fibrous material carbonate filler, a paraffin emulsion madewith a substantially water insoluble type emulsifying agent, and aotential fibre associating agent, and therea er adding to the resultingmix a precipitant for said potential fibre associating agent underconditions favoring the minimizing of the intimacy and time of contactof the constituents of the mix, and thereafter making paper therefrom;

3. The method of sizing paper filled with carbonate filler comprisingmixing in the beater with fibrous material carbonate filler, a paraflinemulsion made with a substantially water insoluble type emulsifyingagent, and a potential fibre associating agent, and thereafter adding tothe resulting mix a precipitant for said potential fibre associatingagent under conditions favoring the minimizing of the intimacy and timeof contact of the constituents of the mix, and thereafter ma ing papertherefrom.

4. The method of sizing paper filled with carbonate filler comprisingmixing with fibrous material carbonate filler, a paraffin emulsion madewith a substantially water insoluble type emulsifying agent, and apotential fibre associating agent in an amount insufficient of itself toimpart substantial sizing to the paper, and thereafter addin to theresulting mix a precipitant for sai potential fibre associating agentunder conditions favoring the minimizing of the time of contact of theconstituents of the mix and thereafter making paper therefrom.

5. The method of sizing paper filled with carbonate filler comprisingmixing with fibrous material carbonate filler, a paraffin emulsion madewith a substantially water insoluble type emulsifying agent, and apotential fibre associating agent, and thereafter adding to theresulting mix a precipitant for said potential fibre associating agentat the wet end of the paper machine.

6. The method ofsizing paper filled with carbonate filler comprisingmixing with fibrous material carbonate filler, a paraffin emulsion madewith a substantially water insoluble type emulsifying agent, and apotential fibre associating agent in an amount insufficient of itself toimpart substantial sizing to the paper, and thereafter adding to theresulting mix a precipitant for said potential fibre associating agentat the Wet end of the paper machine.

7. The method of sizing paper filled with carbonate filler comprisingmixing with fibrous material carbonate filler, a paraffin emulsion madewith a substantially water insoluble type emulsifying agent, and apotential fibre associating agent comprising saponified material, andthereafter adding to the resulting mix a precipitant for said saponifiedmaterial at the wet end of the paper machine.

8. The method of sizing paper'filled with carbonate filler comprisingmixing with fibrous material carbonate filler, a paraffin emulsion madewith .a substantially water insoluble type emulsifying agent, and apotential fibre associating agent comprising soap, 'and thereafteradding to the resulting carbonate-filler comprising mixing with fibrousmaterial carbonate filler, a paraflin emulsion made with a substantiallywater insoluble type emulsifying agent, and a potential fiberassociating agent, and thereafter adding to the resulting mix a salt ofa trivalent metalat the wet end of the paper machine.

11. The method of sizing paper filled with carbonate filler comprisingmixing with fi-v brous material carbonate filler, a paraflin emulsionmade with a substantially water insoluble type emulsifying agent, and apotential fiber associatin agent, and thereafter adding to the resultingmix asalt of aluminum at the wet endv of the paper machine. 12. Themethod of sizing paper filled with carbonate filler comprising mixingwith fibrous material carbonate filler, a parafiin emulsion made with asubstantially water insoluble type emulsifying agent, and a potentialfiber associatin agent, and thereafter adding to-the resu ting mix alumat the wet end of the paper machine.

13. The method of sizing paper filled with carbonate filler comprisingmixing 'with fibrous material-carbonate .filler, a paraifin emulsionmade with a substantially water insoluble type emulsifying agent, andsodium resinate, and thereafter adding alum to the resulting mix at thewet end of the paper machine.

14. The method of sizing paper filled with carbonate filler comprisingmixing with fibrous material carbonate filler, a -paraflin emulsion madewith a substantially water insoluble type emulsifying agent, and sodiumresinate in an amount insuflicient of itself to impart substantialsizing to the paper, and thereafter adding alum to the resulting mix atthe wet end of the paper machine.

, 15. In a method of the character. described, the step of adding aprecipitant at the wet end of the paper machine to a paper mixcontaining fibrous material, carbonate filler,

' a parafiin emulsion made with a substantially water insoluble typeemulsifying agent, and a potential fibre associating agent.

16. In a method of the character described, the step of addin aprecipitant at the wet end of the paper maciine to a paper mixcontaining fibrousmaterial,carbonate filler, a parafiin emulsion madewith a substantially water insoluble type emulsifying agent, and apotential fibre associating agent in an amount insuificient of itself toimpart substantial sizing to the paper.

17. In a method of the character described, the step of adding alum atthe wet end of the paper machine to a aper mix containing fi brousmaterial, carEonate filler, a paraflin emulsion made with asubstantially water insoluble type emulsifying agent, and a potentialfibre associating agent.

18. In a method of the character described, the step of adding aprecipitant at the wet end of the paper machine to a paper mixcontaining fibrous material, carbonate filler, a

parafiin emulsion made with a substantially water insoluble typeemulsifying agent, and saponified material.

19. In a method of the character described, the step of adding alum atthe wet end of the paper machine to a paper mix containing fibrousmaterial, carbonate filler, a paraffin emulsion made with asubstantially water insoluble type emulsifying a ent, and sodiumresinate in an amount insu cient' of itself to impart substantial sizingto the paper.

In testimony whereof I affix my signature. I HAROLD ROBERT RAFTON.

